This invention relates to an assembly for mounting a spray ring or similar device to the duct in a thrust augmentation chamber for a gas turbine aircraft engine.
FIG. 1 is a modified cross-sectional diagram showing a known arrangement for a thrust augmentation combustor for a gas turbine aircraft engine wherein a chamber 10 is surrounded by a duct 12 within which there is provided a combustion liner 14. Spray rings 16 provide fuel to the augmentation combustor. It should be understood in the modified cross-sectional diagram of FIG. 1, only portions of parts immediately adjacent the central cross-section are shown, for simplicity. Fuel supplied by spray rings 16 is mixed into the by-pass air stream by flame holders 20 and ignited by igniting device 22. Spray ring 16 and flame holder 20 surround the tail cone 18 of the turbine portion of the engine.
According to known arrangements, as illustrated in FIG. 2, the fuel spray rings 16 are supported by mounting brackets as shown in FIG. 2. The bracket of FIG. 2 includes a mounting stud 26 for attachment to the peripheral duct 12 of the augmentation combustor. A clevis 24 is attached to the mounting stud 26 and arranged to receive a mounting bracket 28 for mounting the spray ring. Bracket 28 is mounted to clevis 24 by a bolt and pin arrangement whereby bracket 28 can pivot in one rotational direction with respect to clevis 24.
Studies in connection with the engine of FIG. 1 have indicated that augmentation combustion, combined with the operation of the turbine engine, can cause substantial vibrations in duct 12, which may be conducted to augmentation spray ring 16 by reason of the mounting arrangement of FIG. 2. In particular, the FIG. 2 mounting arrangement provides very limited vibration isolation between duct 12 and spray ring 16. Vibrational forces conveyed to spray ring 16 can cause premature failure of the spray ring by reason of resonant vibrations of spray ring 16 leading to structural failure.
It is therefore an object of the present invention to provide a new and improved spray ring mounting arrangement which provides increased isolation of duct vibrations from the spray ring.